Plant deficiency ID: new growth on Java Fern looks "clear" or dark

[Matt Armstrong]

I've got an apparent plant deficiency question that I can't match with plant deficiency charts I find out there such as https://www.aquariumcoop.com/blogs/aquarium/plant-nutrient-deficiencies.

The new growth on my Java Ferns has changed from a green that matches the rest of the plant to a dark/clear color that looks different (see picture). The affected leaves are the first new growth the plant has put out since adding it to the tank -- I watched them unfurl. They began as completely green leaves, and now they're bi-colored as pictured.  Despite this the leaves continue to slowly grow and the largest are now about 1.5 inches.

So, three questions:

1. Has anyone else experienced this?
2. Is it even a problem?
3. What might the problem be?

The tank is a 20 gallon high and has been running, technically, for years but is new to me as of late November.  Mid-december I began dosing Easy Green and the Coop root tabs.  Tank gets 6 hours/day from a Fluval plant LED (the make before their 3.0 version) running at 80% brightness.  No algae problem.

It has an Amazon Sword, purchased some time in August by the prior owner, that was basically floating around the tank unable to root in the 1/2 inch gravel substrate, getting nearly no light, and disintegrating, until I took over the tank, added substrate, added a light and fertilizer. It is now growing rapidly and has shot out a runner.

Early December I added an Anubias, a Bucephalandra, and two Java Ferns. The Anubias hasn't done much, but looks fine. The Buce is sending out new roots.

The Java Ferns were sourced from two places: Petco (which was grown emersed sold in some gel in those sleeve cylinders they sell plants in) and an a local fish store where it was in a tank and looked healthy and like it had been there a while (a low volume LFS in a rural town). Both Java ferns recently began sprouting new leaves and show the same symptoms.

I've read that Java Fern often has issues with Potassium deficiencies. My tank water measures somewhere 2-5 ppm Potassium.

My tap water is soft.  3-4 KH and GH.  Tank water measures similar (I do not run Coral).  Ph is 7.6-7.8.  Water is similar to the Aquarium Coop store and much of the Seattle area.  I don't have coral in the tank.

 

Edited January 11 by Matt Armstrong
wording

[Seattle_Aquarist]

Hi @Matt Armstrong

That is entirely normal for a Java Fern (Leptochilus pteropus, previoudly Microsorum pteropus) that is having healthy growth!  The 'clear' areas will attain 'normal' green color after a few days.  Nice, healthy looking leaves BTW!. -Roy

[Matt Armstrong]

On 1/11/2023 at 4:24 PM, Seattle_Aquarist said:

Hi @Matt Armstrong

That is entirely normal for a Java Fern (Leptochilus pteropus, previoudly Microsorum pteropus) that is having healthy growth!  The 'clear' areas will attain 'normal' green color after a few days.  Nice, healthy looking leaves BTW!. -Roy

Great to hear. Thanks Roy!